1. Field of the Invention
The present invention relates to a method for erasing a disk, and more particularly, to a method for erasing a re-writable disk.
2. Description of the Prior Art
Optical disks have evolved from early read-only disks to writable disks. And moreover, re-writable disks, such as CD-RW disks, are gradually substituting for write-once disks.
Please refer to FIG. 1. FIG. 1 is a block diagram of an information area 10 of a re-writable disk 100. Reference character 10 refers to an information area, starting from t1 to t7. Reference character 20 refers to a test area of a first power calibration area (PCA), starting from t1 to tx. Reference character 30 refers to a counter area of the first PCA, starting from tx to t2. Reference character 40 refers to a program memory area (PMA), starting from t2 to t3. Reference character 50 refers to a lead-in area, starting from t3 to t4. Reference character 60 refers to a program area, starting from t4 to t5. Reference character 70 refers to a lead-out area, starting from t5 to t6. And reference character 80 refers to a second PCA, starting from t6 to t7.
The program area 60 is the area actually used for storing data on the disk 100. The PMA 40 stores information of all tracks on the disk 100. Further, when writing on the disk 100 is finished and the finalization is performed, a table of contents (TOC) will be written in the lead-in area 50, wherein the information of all tracks will be stored in the table of contents as well.
Generally speaking, when an optical disk drive performs an erasing operation, the optical disk drive writes mode 0 data on the disk according to the CD-RW specification. That is, if the optical disk drive detects mode 0 data, the disk is determined to be a blank disk. Moreover, when performing an erasing operation on a re-writable disk, the optical disk drive has a choice to perform a minimum erasing (mini blank) operation or a full erasing (fill blank) operation. The optical disk drive only writes mode 0 data in the PMA and the lead-in area when performing minimum erasing operation. Therefore, when a minimum erased disk is inserted into an optical disk drive, the optical disk drive checks the PMA and the lead-in area, finds mode 0 data, and accordingly determines that the disk is a blank disk. On the other hand, the optical disk drive writes mode 0 data in the program area as well as in the PMA and the lead-in area when performing a full erasing operation. Accordingly, all tracks in the program area record mode 0 data after the full erasing operation.
Please refer to FIG. 2. FIG. 2 is a block diagram of the disk 100 when a fail of writing mode 0 data occurs. When the optical disk drive performs a full erasing operation, mode 0 data will be recorded on tracks in the PMA 40, lead in area 50, and program area 60. When a write fail, such as absolute time in pre-groove (ATIP) unlock interrupt or other errors, occurs during performing an full erasing operation, the optical disk drive issues a write fail message (a servo fail message) to the host. In general, the host will command the optical disk drive to stop performing the full erasing operation after receiving the write fail message, and the host will display information about the blanking fail to the user. Therefore, when a write fail occurs, data in the disk 100 will not be erased completely. For example, assume that a write fail occurs at the location 110 in FIG. 2. Then mode 0 data is already written in the area marked with 105 before the location 110, but the locations after the location 110 (the area marked with 115) still store the original data.